A meandering walk through the net that started at LtU and ended in Source code in Database led me to thinking (again) about how the real visual programming environment should be. And here’s what I came up with:
- It should reflect the fact that code is essentially a graph. It should therefore be basically a graph editor.
- At the single program level, however, this graph is essentially left to right, top to bottom, so a standard representation (as shown by current editors) will be natural
- Folds and hyperlinks are still useful to have around, though; and this represents the 2.5D solution to what is essentially an n-dimensional graph
- It should have the ability to move in at least 3 dimensions - zoom in and out being the 3rd axis. This should behave according to usability principles - zooming way out from a single program should show its package within the other packages’ context, but highlighted; while zooming just a little should show more of the program, but not fold or summarize it in anyway (font zooming goes away completely- we are looking at code, not text)
- Multiple views should always be available - eg, package view must be vieweable as a tree, or a treemap, or a graph, or a list of packages
- editing must be keyboard based to allow for a completely console based implementation if required. The focus is on exposing the true structure of the program, not to sugar coat its display
- Constructing programs must be a structural editing task, not a text editing task.
- language constructs such as keywords, classes, packages etc must act as single “characters” and be deletable atomically.
- since the AST is being represented visually, the editor must provide auto-complete and hints as to expected parts of the current statement being constructed. Eg, typing an “if” or choosing a command to insert an if statement should allow autocomplete to finish choosing if, and provide VB/eclipse style popup hints as to the other components expected.